Polymer composite articles containing polysulfide silicon coupling agents

ABSTRACT

Polymer composites, such as rubber, thermoset and thermoplastic articles, comprising the reaction product of (a) an organic polymer, (b) an inorganic substrate and (c) a polysulfide silicon coupling agent, and articles comprising an inorganic substrate treated with a polysulfide silicon coupling agent.

BACKGROUND OF THE INVENTION

This invention relates to novel polymer composite articles ofmanufacture comprising the reaction product of (a) an organic polymer(b) an inorganic substrate and (c) a polysulfide silicon coupling agent,as well as to articles of manufacture comprising an inorganic substratetreated with a polysulfide silicon coupling agent.

The use of various silicon coupling agents to enhance the adhesion ofvarious inorganic substrates with a broad variety of organic polymers topromote coupling and bonding therewith is well known in the art. Notefor example, U.S. Pat. Nos. 2,832,754; 2,971,864; 3,258,477; 3,661,628;3,671,562; 3,705,911; 3,706,592; 3,754,971; and 4,000,347; and the like.Thus, as is conventionally understood in the art the silicon couplingagent serves as a crosslinker that is chemically or physically bonded toboth the inorganic substrate and the organic polymer in the polymercomposite.

SUMMARY OF THE INVENTION

Accordingly, it is an object of this invention to provide polymercomposite articles of manufacture comprising the reaction product of (a)an organic polymer, (b) an inorganic substrate and (c) a novelpolysulfide silicon composition of matter as disclosed in theconcurrently filed U.S. application Ser. No. 810,785, entitled"POLYSULFIDE SILICON COMPOUNDS" (D-10614) by T. C. Williams and G. E.Totten. It is another object of this invention to provide articles ofmanufacture comprising an inorganic substrate treated with said novelpolysulfide substituted silicon compositions of matter. Other objectsand advantages of this invention will become readily apparent from thefollowing description and appended claims.

More specifically then, one embodiment of this invention relates to apolymer composite article of manufacture comprising the reaction productof (a) an organic polymer, (b) an inorganic substrate, and (c)polysulfide substituted silicon coupling agent selected from the classconsisting of (i) polysulfide substituted silane compounds having theformula ##STR1##

wherein R' is a monovalent radical selected from the class consisting ofhydrogen, hydrocarbon radicals and substituted hydrocarbon radicals;

wherein X is a hydrolyzable radical selected from the class consistingof alkoxy, aryloxy, acyloxy, secondary amino and aminooxy radicals;

wherein R is a divalent bridging group selected from the classconsisting of hydrocarbon radicals, groups of the formula --R"OR"-- andgroups of the formula --R"SR"-- wherein R" is a divalent hydrocarbonradical;

wherein Q is an oxygen atom or a sulfur atom;

wherein Z is a monovalent organic amino radical the nitrogen atom ofwhich is directly bonded to the carbon atom of the (CH₂) group of theabove formula;

wherein n has a value of 0 or 1 and t has a value of 0 or 1, with theproviso that when n is 0, then t is 0; and wherein b has a value of 0 to2, and x has a value of 2 to 4;

(ii)Polysulfide siloxanes consisting essentially of siloxy units havingthe formula ##EQU1## wherein R', R, Q, Z, n, t, b and x are the same asdefined above; and

(iii) polysulfide siloxane copolymers consisting essentially of at leastone siloxy unit represented by formula (A) above and at least one siloxyunit represented by the formula ##EQU2## wherein R' is the same asdefined in formula (A) above and wherein c has a value of from 0 to 3inclusive.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The polymer composite articles of manufacture of this invention cancorrespond to any heretofore conventional polymer composite comprisingan organic polymer bonded to an inorganic substrate through the use ofconventional silicon coupling agents, the difference being that thepolymer composite articles of manufacture of this invention employ asthe coupling agent, the above referred to polysulfide siliconcompositions of matter. Thus, the polymer composite articles ofmanufacture of this invention include such conventional articles asrubber, thermoplastic and thermosetting resins, paints, varnishes, inksand the like.

The organic polymer components of the novel composites of this inventionas well as methods for their preparation are well known in the art andinclude a wide variety of polymers. Illustrative examples of suchpolymers, either singularly or in adjuncture with each other include anyof the homopolymers and copolymers of olefinic and diolefinic monomerssuch as ethylene, propylene, butylenes, methylpentenes, styrene ringsubstituted styrenes, alphamethyl styrene, vinyl chloride, vinylfluoride, vinyllidene chloride, acrylonitrile, methacryhonitrile, vinylalcohol esters, acrylic acid and its esters and amides, methacrylic acidand its esters and amides, allyl phthalate esters, butadiene, isoprene,chloroprene, ethylidene, norbornene, 1,5-hexadiene, divinyl benzenes andthe like, as well as synthetic condensation polymers commonly classed asalkyl resins, polyesters, nylons, phenolics, epoxides polysulfones,polysulfonamides, polysulfides, polyurethanes, polyureas and the like,as well as oligomers and polymers derived from plant and animal sourcessuch as cellulose esters and ethers, carbon-carbon unsaturated fattyacid triglycerides and natural hevea and ficus rubbers and the like.

The more preferred organic polymers employable in this invention are theconventional thermoplastic forming resins, thermoset forming resins, andrubber forming polymers. Illustrative of some of the more preferredthermoplastic forming resins include, e.g. polyethylene, polypropylene,polystyrene, polyvinylchloride, polyvinyl butyral, nylon,polyacrylonitrile, polycarbonates, polyesters, and the like as well ascopolymers and terpolymers thereof. Illustrative of some of the morepreferred thermoset forming resins include, e.g. unsaturated polyesters,epoxides, phenolics, melamine, and the like.

The more preferred organic polymers employable in this invention are theconventional vulcanizable unsaturated rubber polymers used to preparevulcanizable rubber compounds. Illustrative of such vulcanizable rubberpolymers are natural rubber and synthetic rubber polymers as disclosed,e.g. in The Elastomer Manual (1972 Edition) published by InternationalInstitute of Synthetic Rubber Producer, Inc., such as styrene-butadienerubber polymers, butadiene rubber polymers, ethylenepropylene rubberterpolymers, chloroprene rubber polymers, nitrile rubber polymers,bromo- and chloro- butyl rubber polymers, polyisoprene rubber polymers,and the like. Especially preferred are the conventional sulfurvulcanizable rubber polymers such as natural rubber, styrene-butadienerubber polymers, butadiene rubber polymers, and polyisoprene rubberpolymers.

The inorganic substrates employable in this invention are well known inthe art and include any conventional inorganic substrate generallyemployed in rubber, thermoplastic and thermosetting resins, paintsvarnishes, inks and the like, and which are substantially reactivetoward the polysulfide silicon coupling agents employed in thisinvention. Illustrative examples of such inorganic substrates includesuch reinforcing materials, pigments or fillers such as siliceousmaterials such as plate glass, glass fibers, asbestos, sand, clay, talc,silica, e.g. hydrated silica, precipitated silica, fumed silica, silicaaerogels and silica xero-gels, metal silicates, e.g. aluminum siicate,calcium silicate, calcium, metasilicate, magnesium silicate, feldspar,concrete, ceramic materials and the like; metals such as aluminum,copper, cadmium, chromium, magnesium, nickel, silver, tin, titanium,zinc, and the like; the alloys of such metals as brass, bronze, steel,and the like including metals which have been surface treated withphosphates, chromates, and the like; metal oxides such as aluminumoxide, iron oxides, lead oxides, titanium dioxide, zinc oxide and thelike. Of course, it is understood that the particular configuration ofthe inorganic substrate employed is not critical and that the inorganicmaterials can be in any various form such as sheets, plates, blocks,wires, cloth, fibers, filaments, particules, powders and the like. Thepreferred inorganic substrates are the siliceous materials, especiallysilica and metal silicate fillers or pigments.

The polysulfide silicon compositions of matter employable in thisinvention are those polysulfide substituted silanes and siloxanesdisclosed in the concurrently filed U.S. application Ser. No. 810,785.entitled "POLYSULFIDE SILICON COMPOUNDS" (D-10,614) by T. C. Williamsand G. E. Totten, the disclosure of which is encompassed herein byreference thereto.

More specifically such polysulfide silicon compositions of matterinclude polysulfide silane compounds having the formula: ##STR2##wherein R', R, Q, Z, X, t, n, b and x are the same as defined above.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Illustrative radicals represented by R' in formula (I) above arehydrogen and monovalent hydrocarbon radicals which can contain from 1 to20 carbon atoms, which are unsubstituted or substituted with substituteswhich are inert under the reaction conditions employed in preparing thesilane compounds of this invention. Such hydrocarbon radicals includestraight and branched chain alkyl radicals (e.g. methyl, ethyl,n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, n-pentyl, n-hexyl2-ethylhexyl, n-decyl, dodecyl, n-tetradecyl, n-hexadecyl, n-octadecyl,eicosyl and the like); alkenyl radicals (e.g. vinyl, allyl,2,4-hexadienyl, 9, 12, 15-octadecatrienyl, and the like); cycloalkylradicals (e.g. cyclopentyl, cyclohexyl, and the like); cycloalkenylradicals (e.g. 3-cyclohexenyl and the like); aryl radicals (e.g. phenyl,naphthyl, biphenyl, and the like); aralkyl radicals (e.g.p-methylphenyl, p-cyclohexylphenyl, alphamethylnaphthyl, and the like);haloaryl radicals (e.g. 4-chlorophenyl, 2,4-dichlorophenyl,chloronaphthyl, and the like); nitroaryl radicals (e.g. 4-nitrophenyl,and the like); cyanoalkyl radicals (e.g. beta-cyanoethyl,gammacyanopropyl, and the like). Of course, it is understood that eachR' radical can be the same or different in any given silane compound.Preferably R' is hydrogen or a monovalent unsubstituted hydrocarbonradical. More preferably R' is an alkyl radical containing from 1 to 18carbon atoms and most preferably from 1 to 8 carbon atoms.

Illustrative hydrolyzable radicals represented by X in formula (I) aboveinclude alkoxy radicals (e.g. methoxy, ethoxy, propoxy, isopropoxy,2-methoxyethoxy, dodecyloxy, betacyanoethoxy, and the like); aryloxyradicals (e.g. phenoxy, and the like); acyloxy radicals (e.g. formyloxy,acetoxy, and the like); secondary amino radicals such as dialkylamino(e.g. dimethylamino, diethylamino and the like) and aminooxy radicalssuch as dialkylaminooxy (e.g. diethylaminooxy and the like); Of course,it is understood that each X radical can be the same or different in anygiven silane compound, although normally it is preferred that each X bethe same. Preferably X is an alkoxy radical, especially alkoxy radicalsselected from the group consisting of methoxy, ethoxy, and2-methoxyethoxy.

Illustrative divalent bridging radicals represented by R in formula (I)above include hydrocarbon radicals, oxygen containing hydrocarbonradicals (i.e. --R"OR"--) and sulfur containing hydrocarbon radicals(i.e. --R"SR"--). Normally, such radicals contain from 1 to 12 carbonatoms. Illustrative divalent hydrocarbon radicals represented by Rinclude alkylene radicals (e.g. methylene (--CH₂ --), ethylene,propylene, isopropylene, butylene, neopentylene, pentylene,2-ethylhexylene, dodecylene, and the like); arylene radicals (e.g.phenylene, and the like); arylene containing alkylene radicals (e.g.methylenephenylene --(CH₂ C₆ H₄ --), and the like); and the like. Theoxygen containing hydrocarbon radicals represented by R are those of theformula --R"OR"--wherein R" is a divalent hydrocarbon radical such asalkyleneoxyalkylene radicals (e.g. ethyleneoxymethylene (--C₂ H₄ OCH₂--), propyleneoxymethylene (--CH₂ CH₂ CH₂ O--CH₂ --),ethyleneoxyethylene (--C₂ H₄ OC₂ H₄ --), propyleneoxyethylene (--C₃ H₆OC₂ H₄ --), propyleneoxypropylene (--C₃ H₆ OC₃ H₆ --), and the like);aryleneoxyalkylene radicals (e.g. phenyleneoxymethylene (--C₆ H₄ OCH₂--), and the like); and the like. The sulfur (or thio) containinghydrocarbon radicals represented by R are those of the formula --R"SR"--wherein R" is a divalent hydrocarbon radicals such asalkylenethioalkylene radicals (e.g. ethylenethiomethylene (--C₂ H₄ SCH₂--), propylenethiomethylene (--CH₂ CH₂ CH₂ SCH₂ --),propylenethioethylene (--C₃ H₆ SC₂ H₄ --), propylenethiopropylene (--C₃H₆ SC₃ H₆ --), and the like); arylenethioalkylene radicals (e.g.phenylenethiomethylene (--C₆ H₄ SCH₂ --), and the like); and the like.Preferably R is an alkyleneoxyalkylene radical wherein each divalentalkylene radical contains from 1 to 3 carbon atoms, the most preferred Rbridging group being propyleneoxymethylene (--CH₂ CH₂ CH₂ OCH₂ --).

As pointed out above, when n has a value of 0, then t has a value of 0and the silicon atom is directly bonded to the carbon atom of the (CH)group in formula (I) above. However, when n has a value of 1, then t canhave a value of 0 or 1. The preferred silanes of formula (I) above arethose wherein b has a value of 0 and n has a value of 1.

The monovalent organic amino radicals represented by Z in above formula(I) include any organic amino radical derived by removing a hydrogenatom from the nitrogen atom of a corresponding organic primary orsecondary amine employed in the preparation of the amino substitutedmercapto organosilane compounds used to prepare the polysulfide silanesemployable in this invention as explained more fully below. Thus,illustrative monovalent organic amino radicals represented by Z informula (I) include the corresponding organic amino radicals derived byremoving a hydrogen atom from the nitrogen atom of such amines asethylamine, dimethylamine, diethylamine, di-n-butylamine,sec-butylamine, n-octylamine, 2-hydroxyethylamine,bis-(2-hydroxyethyl)amine, 2-methoxyethylamine, 3-hydroxypropylamine,aniline, ortho and para toluidines, ortho and para aminophenols,p-anisidine, p-dimethylaminoaniline, o- and p-chloroanilines,p-acetamidoaniline, benzylamine, o-mercaptoaniline,m-aminophenyltrimethoxysialne, 2-aminopyridine,5-amino-2-mercaptobenzothiazole, cyclohexylamine, cyclohexylmethylamine,N-methylaniline, 2-naphthylamine, ethylenediamine, diethylene triamine,p-phenylenediamine, oxydianiline, 2-mercaptoethylamine, allylamine,3-aminocrotononitrile, piperonylamine, piperazine, piperidine,morpholine, 3-(phenylamino)propyltrimethoxysilane, p-aminodiphenylamine,3-(n-butylamino)propoxytrimethoxysilane, and the like.

Alternatively, then the organic amino radicals represented by Z asdiscussed above may be those of the formula --NZ¹ Z² wherein Z¹ is anorganic radical and Z² is hydrogen or an organic radical when Z¹ and Z²are taken individually, and when Z¹ and Z² are taken together with thenitrogen atom of the above formula they form a heterocyclic radical.

Accordingly, the more preferred polysulfide silane compounds employablein this invention are those having the formula ##STR3## wherein X is ahydrolyzable radical as defined above, especially an alkoxy radical suchas methoxy, wherein R is a divalent alkylene or alkyleneoxyalkylenebridging radical as defined above, especially alkyleneoxyalkyleneradicals, such as propyleneoxymethylene and wherein Z is an organicamino radical as defined above, especially an amino radical of theformula --NZ¹ Z², wherein Z¹ and Z² are taken individually and Z¹ is anorganic radical selected from the class consisting of alkyl, aryl,aralkyl and alkaryl with substituent radicals which do not adverselyaffect the preparation of the silane compounds of this invention, suchas hydroxy, alkoxy, mercapto, amino (e.g. --NH₂, N(CH₃)₂, NHC₆ H₅, NHC₂H₄ N(CH₃)₂ and the like) and hydrolyzable silyl (e.g. --Si(OCH₃)₃)substituted alkyl, aryl, aralkyl and alkaryl radicals, haloaryl (e.g.4-chlorophenyl, etc.) radicals and the like, and wherein Z² is hydrogenor a Z¹ radical as defined above, and wherein x has a value of 2 to 4.

The polysulfide silanes employable in this invention can be convenientlyprepared by heating the novel amino substituted mercapto organosilanesdisclosed in concurrently filed U.S. Application No. 810,840 (D-9978)entitled "AMINO SUBSTITUTED MERCAPTO ORGANOSILICON COMPOUNDS" by T. C.Williams and G. E. Totten in the presence of elemental flowers ofsulfur, the entire disclosure of which is incorporated herein byreference thereto. The amino-catalyzed addition of organic mercaptans toelemental sulfur is well known in the art as seen e.g. by Vineyard, B.D.; "J. Organic Chemistry" 31 p. 601 (1966) and 32, p. 3833 (1967) andthis reaction can be used to prepare the polysulfide silanes employablein this invention, the basic substituent amino group on the startingamino substituted mercapto organosilanes allowing the reaction to beautocatalytic. Thus, the process factors involved in forming thepolysulfide silanes are not critical. Said process basically involvesmerely refluxing two moles of the amino substituted mercaptoorganosilane in the presence of flowers of sulfur and in the furtherpresence or absence of an organic solvent until the desired polysulfidesilane is produced. Generally, it is preferred to carry out the processin the presence of an organic solvent and any suitable solvent such asmethanol, methylene chloride and the like can be employed. Completion ofthe reaction is easily determined by the absence of any further H₂ Sby-products given off and said reaction is generally completed withinfive hours. The amount of sulfide employed is not narrowly critical andneed only be that amount sufficient to provide a polysulfide group of atleast two sulfur atoms. Normally, amounts of sulfur sufficient toprovide a polysulfide group of more than four sulfur atoms areunnecessary and wasteful although such higher amounts can be used ifdesired. Of course, it is obvious that the preferred reaction conditionsfor any particular polysulfide silane product can be easily determinedby routine experimentation. The solvent if employed can be easilyremoved by distillation and the polysulfide product recovered by anysuitable method. While the polysulfide silanes employable in thisinvention can be employed in their crude product form, if desired, theymay be purified by conventional procedures.

As pointed out above, the starting silanes employed in preparing thepolysulfide silanes employable in this invention are those aminosubstituted mercapto organosilanes disclosed in said concurrently filedU.S. application Ser. Nos. 810,840 (D-9978) and 810,785 (D-10,614).

More specifically such amino substituted mercapto organosilane compoundsare those having the formula: ##STR4## wherein X, R', R, Q, Z, b, n, andt are the same as defined in formula (I) above.

Such amino substituted mercapto organosilanes employable in thisinvention can be prepared by reacting the novel episulfide substitutedorganosilanes disclosed in concurrently filed U.S. application Ser. No.810,851 entitled "Episulfide Substituted Organosilicon Compounds"(D-9972) by T. C. Williams and G. E. Totten the disclosure of which isencompassed herein by reference thereto, with a primary or secondaryamine as described in said concurrently filed U.S. application Ser. No.810,840 (D-9978) and shown by the following equation: ##STR5## whereinX, R', R, Q, b, n and t are the same as defined in formula (I) above andH-N< is a primary or secondary amine. More specifically said process canbe illustrated as follows: ##STR6##

As seen by the above equations the episulfide (or thiiranyl) group onthe silane is opened to form the desired mercapto radical (--SH) andprovide the bonding to the amino radical derived from the primary orsecondary amine reactant, thus resulting in the desired correspondingamino substituted mercapto organo silane products.

Any organic primary or secondary amine which will function as describedabove in process (II) may be employed to prepare said amino substitutedmercapto organosilanes and such amine compounds and/or methods for theirpreparation are well known in the art. Illustrative examples of suchprimary and secondary amine reactants include such amines asmethylamine, ethylamine, dimethylamine, diethylamine, di-n-butylamine,sec-butylamine, n-octylamine, 2-hydroxyethylamine,bis-(2-hydroxyethyl)amine, 2-methoxyethylamine, 3-hydroxypropylamine,aniline, ortho and para toluidines, ortho and para aminophenols,p-anisidine, o-dimethylaminoaniline, o- and p- chloro anilines,p-acetamidoaniline, benzylamine, o-mercaptoaniline,m-aminophenyltrimethoxysilane, 2-aminopyridine,5-amino-2-mercaptobenzothiazole, cyclohexylamine, cyclohexylmethylamine,N-methylaniline, 2-naphthylamine, ethylenediamine, diethylene triamine,p-phenylenediamine, oxydianiline, 2-mercaptoethylamine, allylamine,3-aminocrotononitrile, piperonylamine, piperazine, piperidine,morpholine, 3-(phenylamino)propyltrimethoxysilane, p-aminodiphenylamine,3-(n-butylamino)propyltrimethoxysilane, and the like.

The process factors involved in forming said amino substituted mercaptoorganosilanes by the above described process are not critical althoughcertain practical choices may be made as described below.

As pointed out above, process (II) merely involves reacting acorresponding episulfide substituted silane with an organic primary orsecondary amine and maintaining the reaction until the episulfide grouphas been opened to form the desired amino substituted mercaptoorganosilane. No special catalysts are needed for the process. It isadvantageous, however, to carry out the process in the presence of asolvent such as hydrocarbons, ethers, esters, alcohols and mixturesthereof. The amount of solvent used is not narrowly critical, thesolvent normally being employed in an amount sufficient to dissolve thereactants involved, although lower or higher amounts can be employed ifdesired. Of course, it is to be understood that the solvent employedshould be chosen so as to not adversely react with the hydrolyzablegroups on the starting silane or otherwise adversely affect the desiredreaction.

In general, process (II) merely involves mixing both reactants and thesolvent and maintaining the resultant solubilized mixture at thereaction temperature until the reaction has been completed. Preferablythe amount of organic amine employed is at least stoichiometricallyequivalent to the number of episulfide groups of the silane to bereacted or moderately in excess of such amounts, although higher orlower amounts of the organic amine may be employed if desired. Theprocess is generally conducted at atmospheric pressure, althoughsubatmospheric or superatmospheric pressures may be used if desired. Itis also preferred that said process be initially conducted in asubstantially anhydrous environment due to the reactivity of thereactants and products towards water, thus the process is normallycarried out under a dry nitrogen atmosphere.

The reaction temperature in above described process (II) is not narrowlycritical and can range from about room temperature up to and includingthe reflux temperature of the reaction mixture as may be convenient forthe operator, the most preferred reaction temperature for any specificreaction being obviously easily determinable by routine experimentation.The process is generally completed within from about one to about fourhours, but may be completed faster or take longer depending on suchobvious factors as the amounts and types of reactants involved and thesolvent and reaction temperature employed. Completion of the reaction iseasily determinable e.g. by infrared analysis on a sample of thereaction product for the presence of the mercapto group or by titrationof such a sample for the presence of said mercapto group. The solventemployed in the process can be easily removed and the desired aminosubstituted mercapto organosilane products recovered by any suitableconventional method. For example, the solvent can be removed bystripping at reduced pressures. The amino substituted mercaptoorganosilanes employable in this invention can be advantageouslyemployed in their crude product form or, if desired, undergoconventional treatment procedures in order to obtain a purer productprior to use.

As pointed out above, said amino substituted mercapto organosilanes areprepared from the novel episulfide substituted organosilanes disclosedin said concurrently filed U.S. application Ser. Nos. 810,851 (D-9972)and 810,785 (D-10,614).

More specifically, such episulfide substituted organosilane compoundsare those having the formula: ##STR7## wherein X, R', R, Q, b, n and tare the same as defined in formula (I) above.

Preferably the episulfide substituted organosilanes are prepared byreacting a corresponding epoxide containing silane with thiourea asshown by the following equation: ##STR8## wherein X, R', R, Q, b, n andt are the same as defined above. More specifically said process can beillustrated as follows: ##STR9##

Alternatively the episulfide substituted organosilanes can also beprepared by reacting a corresponding epoxide containing silane with ametal thiocyanate salt as shown by the following equation: ##STR10##wherein X, R', R, Q, b, n and t are the same as defined above and M is ametal such as an alkali metal. More specifically said process may beillustrated as follows: ##STR11##

As seen by the above equations the oxygen atom of the epoxide radical ofthe starting material is replaced by the sulfur atom of the thiourea ormetal thiocyanate salt to form the desired episulfide radical, thusresulting in the desired corresponding episulfide substituted silaneproducts.

The reaction compounds, i.e. epoxide containing silanes, thiourea, ormetal thiocyanate salts and/or methods for their production, which canbe used in the above described processes (III) and (IV) are well knownin the art. Illustrative metal thiocyanate salt starting materialsinclude e.g. the alkali metal thiocyanates such as NaSCN, KSCN and thelike.

The process factors involved in forming the episulfide substitutedorganosilanes by either of the above two described preferred methods(III) and (IV) are not critical although certain practical choices maybe made as described below;

As pointed out above, the two methods of preparation merely involvereacting a corresponding epoxide containing silane with thiourea(Process (III)) or a metal thiocyanate salt (Process (IV)) andmaintaining the reaction until the oxygen atom of the epoxide startingmaterial has been replaced with the sulfur atom of the thiourea or metalthiocyanate salt to form the desired episulfide substitutedorganosilane.

No special catalysts are needed for either process. It is advantageous,however, to employ a polar solvent. Suitable solvents include aliphaticalcohols such as methanol, ethanol, n-propanol, t-butanol and the like.The amount of solvent used is not narrowly critical the solvent normallybeing employed in an amount sufficient to dissolve the reactantsinvolved, although lower or higher amounts can be employed if desired.Of course, it is to be understood that the solvent employed should bechosen so as to not adversely react with the hydrolyzable groups on thestarting silane or otherwise adversely affect the desired reaction.

In general, both processes (III) and (IV) described above merely involvemixing both reactants and the solvent and maintaining the resultantsolubilized mixture at the reaction temperature until the reaction hasbeen completed. Any convenient order of mixing can be employed. In bothprocesses stoichiometric amounts of reactants can be used, while it maysometimes be advantageous to use an excess of urea or metal thiocyanatein order to increase the yield or the reaction rate. Both processes aregenerally conducted at atmospheric pressure, although subatmospheric orsuperatmospheric pressures may be used if desired. It is also preferredthat said processes (III) and (IV) be initially conducted in asubstantially anhydrous environment due to the reactivity of thereactants and products towards water thus both processes are normallycarried out under a dry nitrogen atmosphere.

The reaction temperature for both processes (III) and (IV) are notnarrowly critical and can range from about room temperature up to andincluding the reflux temperature of the reaction mixture as may beconvenient for the operator, the most preferred reaction temperature forany specific reaction being obviously easily determinable by routineexperimentation. Both processes (III) and (IV) are generally completedwithin from about one to about four hours but may be completed faster ortake longer depending on such obvious factors as the amounts and typesof reactants involved, and the solvent and reaction temperatureemployed. Completion of said reactions is easily determinable, e.g. bythe cessation of any further formation of undesirable solid urea orcyanate salt by-product. The solvent employed and the by-products ofsaid preferred processes (A) and (B) can be easily removed, and thedesired normally liquid episulfide substituted silane products recoveredby any suitable conventional method. For example, the solvent can beremoved by distillation and the solid by-products by filtration,centrifuging and the like. While the episulfide substitutedorganosilanes can be advantageously employed in their crude productform, or they can, if desired, undergo conventional treatment proceduresin order to obtain a purer product prior to use.

Illustrative polysulfide silanes that may be derived from theircorresponding amino substituted mercapto organosilane starting materialsinclude ##STR12## and the like.

Alternatively the silicon coupling agent compositions of matteremployable in this invention include polysulfide siloxanes. Illustrativeof such polysulfide siloxanes are those consisting essentially of siloxyunits having the formula ##EQU3## wherein R', R, Q, Z, n, t, b and x arethe same as defined above; as well as polysulfide siloxane copolymersconsisting of at least one siloxy unit represented by formula (A) aboveand at least one siloxy unit represented by the formula: ##EQU4##wherein R' is the same as defined in formula (A) above, and wherein chas a value of from 0 to 3 inclusive.

For example, the polysulfide silanes of this invention can be hydrolyzedand condensed in the conventional manner, either alone or together withother hydrolyzable silanes to produce siloxanes consisting essentiallyof the siloxy units of formula (A) above or copolymer siloxanesconsisting essentially of siloxy units of formula (A) above and formula(B) above. When the polysulfide silanes of this invention arecohydrolyzed and condensed with other conventional hydrolyzable silanes,the siloxanes produced are copolymers composed essentially of siloxyunits of formula (A) above and formula (B) above. Illustrativeconventional hydrolyzable silanes are those of the formula R'_(c)-Si-X_(4-c) wherein R' and c are the same as defined above and X is ahydrolyzable group such as an alkoxy radical, e.g. methoxy.

Thus, in general the polysulfide siloxanes must contain at least onesiloxy unit such as ##STR13## may contain one or more siloxy units, suchas R'₃ SiO₀.5, R'₂ SiO, R'SiO₁.5, or SiO₂, wherein Z, Q, R, R', t, n andx are the same as defined above. Of course, it is understood that thesiloxanes can also contain a minor amount of hydrolyzable groups ifcomplete hydrolysis is not obtained.

The hydrolysis and condensation of the polysulfide silanes of thisinvention are not critical and can be carried out in any conventionalmanner, and such procedures are well known in the art. Alternatively,the polysulfide siloxanes of this invention can also be prepared byreacting a corresponding amino-substituted mercapto organosiloxane inthe same manner as described above for producing the polysulfide silanesof this invention. However, it is to be understood that when suchalternative method is employed the siloxanes of this invention cancontain hydrolyzable end blocked siloxy units if the starting materialscontain same as well as minor amounts of siloxy units having unreactedamino and mercapto substituted organo groups if the reaction isincomplete.

Elemental analysis, C¹³ nuclear magnetic resonance spectroscopy andproton nuclear magnetic resonance spectroscopy confirmed that thepolysulfide silane compositions of matter of this invention consistessentially of compositions having the general formula (I) employedherein above. It is to be understood, of course, that since the aminosubstituted mercapto organo-silicon starting materials may contain minoramounts of mercapto groups bonded directly to the (CH₂) group of saidformula (I) and like amounts of the amino radical bonded directly to the(CH) group of said formula (I) then the polysulfide silicon compositionsof this invention may also contain minor amounts (normally not more than10%) of the polysulfide groups bonded directly to said (CH₂) group andlike amounts of the amino radical bonded directly to said (CH) group.

The function of a silicon coupling agent to provide a strong chemicalbridge between the inorganic substrate and the organic polymer employedis well known in the art. It is of course understood that for effectivecoupling action in a particular polymer substrate composite, it isnecessary to select the appropriate coupling agent, i.e. one which issuitable reactive towards both the polymer component and the substratecomponent for each particular polymer-substrate composite considered.Thus, while there may be more than one appropriate coupling agent for aparticular polymer substrate composite, a given coupling agent may notbe appropriate for all polymer composites. However, the selection of themost preferred coupling agent for any particular polymer composite iswell within routine experimentation.

The particular manner of compounding the polymer composite articles ofmanufacture of this invention as well as the various amounts ofingredients employed are not critical and merely depend on theparticular finished polymer composite desired along with the ultimateend use for which it is to be employed and such steps as compounding,heating, crosslinking or vulcanizing, and the like, may be conducted inany conventional manner heretofore employed in preparing conventionalpolymer composites such as thermoplastic resin composites, thermoset,resin composites, vulcanized rubber composites, and the like.

For example, in the case of conventional polymer-filler type compositessuch as vulcanized rubber articles the polysulfide organosiliconcoupling agents and/or solubilized solutions thereof can be added to thevulcanizable rubber polymer batch together with the substrate filler andvarious other additives during mill or banbury mixing. Alternatively,the substrate fillers or vulcanizable rubber polymers can be treated(coated) with the polysulfide organosilicon coupling agents and/orsolubilized solutions thereof prior to incorporation into the rubberpolymer or filler master batch. Generally, it is preferred to employ thepolysulfide organosilicon coupling agents neat, mix them with thesubstrate filler, preferably a silica or metal silicate filler, and addthe mixture to the polymer batch prior to the incorporation of the otherconventional additives normally employed in such polymer filledcomposites. Moreover, if desired, the polysulfide organosilicon couplingagents can be taken up (absorbed) on any suitable conventionalmicroporous carrier, e.g. Microcel E, a calcium silicate, prior to useto form a dry free flowing powder concentrate. Such microporouscarriers, in the amounts normally used, do not affect the properties ofthe composite product articles and the free flowing powder concentrateprovides convenience in handling and metering of the coupling agent. Aspointed out above, the particular procedures involved and amount ratiosof the components employed are all within the knowledge of one skilledin the art and are left to the choice of the operator. Morespecifically, however, the preferred polymer composite articles of thisinvention are vulcanized rubber articles. Thus, in general, the amountof polysulfide organosilicon coupling agent employed in the vulcanizedrubber composites of this invention will normally range from about 0.1to about 20 parts by weight (preferably from about 0.2 to about 10 partsby weight) per 100 parts by weight of inorganic substrate filleremployed although higher or lower amounts may be employed if desired. Ofcourse, the amount of inorganic substrate filler employed merely dependson the desired rubber product end use and may range from about 5 up toas high as 300 parts by weight or higher per 100 parts by weight ofvulcanized rubber polymer employed. The vulcanizable rubber compound isnormally vulcanized in the presence of conventional sulfur or peroxidecuratives that are well known in the art. For example, a conventionalsulfur curative may include per 100 parts by weight of vulcanizablerubber polymer from about 0.5 to 4 parts by weight of sulfur, about 2 to5 parts by weight of zinc oxide, and about 0.2 to 3 parts by weight ofaccelerators (e.g. diphenylguanidine); while a conventional peroxidecurative generally may include per 100 parts by weight of vulcanizablerubber polymer from about 1 to about 8 parts by weight of an organicperoxide e.g. dicumyl peroxide, α,α'-bis(t-butyl peroxy)diisopropylbenzene, and the like. The vulcanization procedure of arubber polymer is well known in the art and in general may be conductedat temperatures ranging from 260° F. to about 360° F. although lower orhigher temperatures may be employed if desired. Of course, it is obviousthat if desired the vulcanized rubber composites of this invention maycontain any of the conventionally additional ingredients such asextenders, carbon blacks, processing oils, plasticizers, antioxidants,lubricants, accelerators, retardants, coloring pigments and dyestuffsand the like, normally employed in conventional vulcanized rubbercomposites and such is well within the knowledge of one skilled in theart.

In the case of conventional rubber, thermoplastic or thermoset polymerlaminate type composites wherein e.g. the inorganic substrate is glassfibers, it is generally preferred to pretreat (coat) the inorganicsubstrate with the polysulfide organosilicon coupling agent prior tobonding with the organic polymer employed although the coupling agentand organic polymer can be deposited together on the substrate and thenbonded or the polymer first treated with the coupling agent and thencoated onto the substrate and bonded, it desired. The polysulfideorganosilicon coupling agent may be employed neat, although it isgenerally preferred to employ a solubilized solution of the couplingagent by employing an appropriate solvent such as those discussed above,and more preferably to employ an aqueous composition of the polysulfideorganosilicon coupling agent, especially the silane coupling agents. Theproduction of such polymer laminate type composites is well known in theart. The various amounts of compounds employed of course merely dependupon the polysulfide organosilicon coupling agent employed, the surfacearea to be covered, the organic polymer to be bonded to the substrateand the like. Moreover, the method of coating the substrate is notcritical and the coupling agent can be sprayed, brushed, poured, orrolled on to the surface to the substrate and the like, or alternativelythe substrate can be dipped into a solvent solution or aqueouscomposition of the coupling agent. Likewise, the temperature at whichthe bonding reaction is carried out can be varied over a wide rangedepending upon the specific compounds employed. In general, heattemperatures will generally be in the range of about 100° C. to about350° C. or higher, although if desired the bonding between thesubstrate, coupling agent and organic polymer may also be carried out bythe use of ultra-violet radiation, X-rays, and the like. Of course, itis obvious that such polymer laminate type composites if desired maycontain any of the conventional additional ingredients normally employedin conventional polymer-laminate articles such as catalysts,antioxidants, pigments, and the like.

Accordingly, another aspect of this invention is directed to aninorganic substrate as defined above treated with polysulfideorganosilicon coupling agent as defined above. When employed aqueouscompositions of the coupling agent generally comprise from about 0.1 toabout 20 parts by weight of the polysulfide organosilicon coupling agentand from about 99.9 to about 80 parts by weight of water. Such aqueouscompositions may be in the form of solutions, dispersions or emulsionsand may be especially suitable for use as sizing and finishing agents inthe glass fiber industry. If desired the polysulfide organosiliconcoupling agent can be employed in the form of a water-soluble solventsolubilized solution. Generally, it is preferred to employ aqueouscompositions of a polysulfide organosilane coupling agent. Of course, itis to be understood that since the polysulfide organosilicon couplingagents contain hydrolyzable groups (e.g. alkoxy radicals) the aqueouscompositions of such include and encompass, the hydrolyzates, partialhydrolyzates, condensates and partial condensates of said siliconcoupling agents. The treatment or coating of the inorganic substratewith said aqueous compositions is conventional as discussed above.

Thus, it will be readily apparent to those skilled in the art that thepolysulfide organosilicon coupling agents employed in this inventionlend themselves to any conventional process where organic polymers areto be bonded to inorganic substrates and thus to the formation of a widerange of polymer composite articles of manufacture such as filledvulcanized rubber products, filled thermoset and thermoplastic products,organic polymer-substrate (e.g. glass fibers) laminate products, and thelike, heretofore prepared with conventional silane coupling agents.

Evidence of action by a coupling agent is manifested through changes incomposite properties away from the values displayed in the absence ofthe agent and the properties which may be favorably altered are many andvaried. In elastomeric and resinous composites the improved effectsattributable to the instant invention are often seen in terms of itsincreased resistance to deforming forces and abrasion resistance and indecreased hysteresis losses in flexure. For example, the reactivityand/or bonding between the organic polymer, inorganic substrate andpolysulfide organosilicon coupling agent of this invention isdemonstrated by improved physical properties in the finished polymercomposite product, such as tensile modulus, and the like as compared tothe physical properties of the same finished composite product preparedwithout the use of the polysulfide organosilicon coupling agent.Likewise, while the polysulfide organosilicon "coating" per se on thepretreated inorganic substrate articles of this invention is notmeasurable, its presence is also confirmed by such improved physicalproperties in the finished polymer composite prepared with suchpretreated substrates as compared to the same finished product preparedwith an untreated substrate and without the use of any polysulfideorganosilicon coupling agent.

The following examples are illustrative of the present invention and arenot to be regarded as limitative. It is to be understood that all parts,percentages and proportions referred to herein and in the claims are byweight unless otherwise indicated. Tensile modulus is defined as tensilestress in pounds per square inch of original cross-sectional areanecessary to produce a given extension in a composite specimen, usually300% of the unstressed length.

EXAMPLE 1

Into a 1-liter, 3-neck flask equipped with a magnetic stirrer,thermometer, and a reflux condenser having a nitrogen by-pass forcarrying out the reaction under a nitrogen atmosphere were charged about269.6 grams of distilled glycidoxypropyltrimethoxysilane, about 86.9grams of thiourea and about 312.2 grams of methanol. The stirredsolubilized reaction mixture was boiled at reflux (about 65° C.) for onehour, then cooled and the methanol solvent stripped out under reducedpressure. The reaction product mixture was then dissolved in diethylether and then washed with water to remove the precipitated ureaby-product and any unreacted thiourea. The ether solution was then driedwith anhydrous magnesium sulfate, filtered, and the ether stripped offunder reduced pressure to yield about 234.4 grams of the desired fluid1,2-epithio-4-oxa-7-trimethoxysilyl heptane crude product which has theformula ##STR14## The structure of said crude product was confirmed byinfrared absorption spectroscopy, proton magnetic resonance spectroscopyand C¹³ magnetic resonance spectroscopy analysis, as well as by chemicalanalysis for methoxy and elemental silicon content.

About 40 grams of said crude product were then distilled through a1-foot Vigreaux column at about 0.18 mm Hg. to yield about 35.6 grams ofyellow-white viscous 1,2-epithio-4-oxa-7-trimethoxysilyl heptane oilhaving boiling points of about 95° C. at 0.07 mm Hg. and about 108° C.at 0.18 mm Hg. and a refractive index of n_(D) ²⁰ =1.460. The structurefor said distilled 1,2-epithio-4-oxa-7-trimethoxysilyl heptane productwas confirmed by C¹³ nuclear magnetic resonance spectroscopy, laserRaman spectroscopy and vapor phase chromatography.

EXAMPLE 2 Preparation of1-dimethylamino-2-mercapto-4-oxa-7-(trimethoxysilyl) heptane

In a 500 cc flask equipped with thermometer, condenser, magneticstirrer, heater, N₂ atmosphere and dropping funnel were placed 50.0parts by weight of hexane plus 7.0 parts by weight of dimethylamine.While gently warming to about 46° C., 25.2 parts by weight of a crude1,2-epithio-4-oxa-7-trimethoxysilyl heptane product, prepared asdescribed in Example 1 above, was added dropwise. The mixture was boiledat reflux (57° C.) for three hours, cooled and the solvent strippedunder reduced pressure. A slight turbidity in the mixture, apparentlydue to polymer formation was removed by filtration. Analysis by C¹³ andproton nuclear magnetic resonance spectroscopy and by chemicaltitrations for mercapto and amino content of the product confirmed thatan amino substituted mercapto organosilane having the formula

    (CH.sub.3 O).sub.3 Si(CH.sub.2).sub.3 OCH.sub.2 CH(SH)CH.sub.2 N(CH.sub.3).sub.2

was produced in an 80% yield (based on titration for the mercaptogroup).

EXAMPLE 3 Preparation ofbis-[1-dimethylamino-4-oxa-7-(trimethoxysilyl)-2-heptane]disulfide.

In a 25 cc flask equipped with a thermometer, condenser, magneticstirrer, heater, nitrogen sparge tube to facilitate removal of hydrogensulfide, and a dropping funnel were placed 1.15 parts by weight ofelemental sulfur (Niagara Rubbermakers #104) and 50.0 parts by weight ofmethylene chloride. Nitrogen was bubbled very gently into the reactionmixture and with stirring 25.0 parts by weight of1-dimethylamino-2-mercapto-4-oxa-7-(trimethoxysilyl) heptane (preparedas described in Example 2) were added dropwise at ambient temperature.The reaction mixture was stirred at ambient temperature for one hour andthen boiled at reflux for four hours, cooled and the solvent strippedoff under reduced pressure. Analysis by C¹³ nuclear magnetic resonancespectroscopy and by chemical titrations for amino and residual thiolgroups as well as the sulfur to silicon ratio of the crude productconfirmed that a polysulfide silicon compound having the formula##STR15## was produced in a 93% yield.

EXAMPLES 4 TO 8

A variety of polysulfide silane compounds were prepared according to thegeneral procedure of Example 3 above using either a1-dimethylamino-2-mercapto-4-oxa-7-(trimethoxysilyl) heptane productprepared as described in Example 2 above (i.e. the starting silanematerial in Example No. 4 of TABLE I below), or a1-piperidino-2-mercapto-4-oxa-7-(trimethoxysilyl) heptane productprepared according to the general procedure of Example 2 above and asdescribed in Example 4 of applicants' said concurrently filed U.S.application Ser. No. 810,840 (D-9978) (i.e. the starting silane materialin Examples Nos. 5 and 6 of TABLE I below), or a1-anilino-2-mercapto-4-oxa-7-(trimethoxysilyl) heptane product preparedaccording to the general procedure of Example 2 above and as describedin Example 6 of applicants' said concurrently filed U.S. applicationSer. No. 810,840 (D-9978) (i.e. the starting silane material in ExamplesNos. 7 and 8 TABLE I below). Analysis by C¹³ and proton nuclear magneticresonance spectroscopy as well as titration for residual thiol groupsconfirmed that the polysulfide products of each example were allobtained in greater than 95% yields.

                                      TABLE I                                     __________________________________________________________________________                              Parts                                                                            Sulfur*                                                                            Solvent                                                               by (Parts By                                                                          (Parts                                      Ex. No.                                                                            Amino, Mercapto Silane                                                                             Wt.                                                                              Wt.) By Wt.)   Polysulfide Silane                __________________________________________________________________________                                                Product                                 ##STR16##           25.0                                                                             2.3  Methylene Chloride (50.0)                                                                ##STR17##                        5                                                                                   ##STR18##           25.8                                                                             1.1  Methanol (50.0)                                                                          ##STR19##                        6                                                                                   ##STR20##           20.0                                                                             1.7  Methylene Chloride (100.0)                                                               ##STR21##                        7                                                                                   ##STR22##           29.8                                                                             1.1  Methanol (50.0)                                                                          ##STR23##                        8                                                                                   ##STR24##           15.3                                                                             1.2  50% Methanol/ 50% Methylene Chloride                                          (200.0)                                                                                  ##STR25##                        __________________________________________________________________________     *Elemental Sulfur (Niagara Rubber maker #104)                            

EXAMPLES 9-15

A variety of silica-filled rubber compounds were prepared using theformulations of TABLE II and the same procedure. The silane couplingagents employed were the polysulfide silane products of Examples 3 to 8above and are identified as Silanes A to F respectively in TABLE IIIbelow. Thus, said Silanes A to F have the structural formulas given forthe products in above Examples 3 to 8 respectively.

                  TABLE II                                                        ______________________________________                                        Formulation         (Parts by Weight)                                         ______________________________________                                        Styrene-Butadiene Rubber.sup.1                                                                    100                                                       Silica Filler.sup.2 35                                                        Silane Coupling Agent                                                                             Varied*                                                   Softener Oil.sup.3  8.0                                                       BBS.sup.4           1.2                                                       DOTG.sup.5          2.5                                                       Sulfur              1.6                                                       Zinc Oxide          4.0                                                       Stearic Acid        1.0                                                       ______________________________________                                         .sup.1 SBR 1502                                                               .sup.2 Precipitated silica (HiSil 233, Trademark of PPG Industries, Inc.)     .sup.3 Sundex 790, an aromatic processing oil (Trademark of Sun Oil Co.)      .sup.4 N-t-butyl-2-benzothiazole sulfenamide                                  .sup.5 Di-ortho-tolyl guanidine                                               *As shown in Table III below.                                            

Each formulation was prepared using a 2 roll rubber mill having a rolltemperature of about 130° F. The rubber polymer was charged to therubber mill and milled until smooth and plastic. Then a small portion ofthe filler was added to the polymer band, followed by the addition ofmore filler along with the silane coupling agent which was addeddropwise and concurrently with the filler. After all the silane andabout half of the filler had been added the softening oil was addedconcurrently with the remainder of the filler. After an intimate milledmixture of the styrenebutadiene rubber, silica filler, silane couplingagent and softener was obtained, the sulfur, accelerators and otherancillary ingredients were added and the mixture further milled until anintimate dispersion was obtained. After storing at ambient roomconditions for at least 16 hours, the mixture was remilled untilplastic. Molded preformed sheets were cut from the remilled mixture ofeach formulation and then vulcanized in the same manner in a mold underpressure at 320° F. to 340° F. After resting at ambient room conditionsfor at least 16 hours the physical properties of the vulcanized moldedrubber composites were then measured and the results recorded as shownin TABLE III.

                                      TABLE III                                   __________________________________________________________________________       Silane   300%                                                              Ex.                                                                              Coupling Agent                                                                         Tensile Modulus                                                                        Tensile Strength                                                                       Elongation at Break                                                                     Tear Strength                         No.                                                                              (Parts by Wt.)                                                                         (psi).sup.1                                                                            (psi).sup.1                                                                            (%).sup.1 (psi).sup.2                           __________________________________________________________________________    9  Control-No Silane                                                                      320      2480     800       160                                   10 Silane A (1.86)                                                                        510      3660     720       340                                   11 Silane B (1.90)                                                                        490      3860     760       240                                   12 Silane C (1.97)                                                                        470      3660     730       230                                   13 Silane D (4.60)                                                                        520      3270     730       240                                   14 Silane E (1.98)                                                                        450      3600     750       220                                   15 Silane F (4.60)                                                                        520      3100     700       230                                   __________________________________________________________________________     .sup.1 Tested in compliance with ASTM D412.                                   .sup.2 Tested in compliance with ASTM D624.                              

The above data demonstrates a significant improvement in the tensilemodulus of the silane containing vulcanized rubber compound of Examples10 to 15 over the non-silane containing vulcanized rubber compound ofcontrol Example 9.

As noted above, the polysulfide silane compositions of matter areextremely effective coupling agents and thus offer exceptional promisein the production of filled-vulcanized rubber articles such as tires,gaskets, hoses and other conventional mechanical rubber goods.

Various modifications and variations of this invention will be obviousto a worker skilled in the art and it is to be understood that suchmodifications and variations are to be included within the purview ofthis application and the spirit and scope of the appended claims.

What is claimed is:
 1. An inorganic substrate treated with a polysulfidesilicon coupling agent selected from the class consisting of (i)polysulfide silanes having the formula ##STR26## wherein R' is hydrogenor a monovalent radical selected from the class consisting ofhydrocarbon radicals and substituted hydrocarbon radicals;wherein X is ahydrolyzable radical selected from the class consisting of alkoxy,aryloxy, acyloxy, secondary amino and aminooxy radicals; wherein R is adivalent bridging group selected from the class consisting ofhydrocarbon radicals, groups of the formula --R"OR"-- and groups of theformula --R"SR"-- wherein R" is a divalent hydrocarbon radical. whereinQ is an oxygen atom or a sulfur atom; wherein Z is a monovalent organicamino radical the nitrogen atom of which is directly bonded to thecarbon atom of the (CH₂) group of the above formula; wherein n has avalue of 0 or 1 and t has a value of 0 or 1, with the proviso that whenn is 0, then t is 0; and wherein b has a value of 0 to 2, and x has avalue of 2 to 4; (ii) polysulfide siloxane homopolymers consistingessentially of siloxy units having the formula ##STR27## wherein R', R,Q, Z, n, t, b and x are the same as defined above; and (iii) polysulfidesiloxane copolymers consisting essentially of at least one siloxy unitrepresented by formula (II) above and at least one siloxy unitrepresented by the formula ##STR28## wherein R' is the same as definedin formula (II) above, and wherein c has a value of from 0 to 3inclusive.
 2. An inorganic substrate as defined in claim 1 wherein thesubstrate is a siliceous reinforcing material.
 3. An inorganic substrateas defined in claim 2 wherein the polysulfide silicon coupling agent isa polysulfide silane having the formula ##STR29##
 4. An inorganicsubstrate as defined in claim 3 wherein R' is an alkyl radical, whereinX is an alkoxy radical, wherein R is an alkylene or alkyleneoxyalkyleneradical, wherein n is 1, and t is 0, wherein Z is an organic aminoradical of the formula --NZ¹ Z² wherein Z¹ and Z² are taken individuallyand Z¹ is an organic radical selected from the class consisting ofalkyl, aryl, aralkyl, alkaryl and haloaryl radicals, hydroxy substitutedalkyl, aryl, aralkyl and alkaryl radicals, alkoxy substituted alkyl,aryl, aralkyl and alkaryl radicals, mercapto substituted alkyl, aryl,aralkyl and alkaryl radicals, and hydrolyzable silyl substituted alkyl,aryl, aralkyl and alkaryl radicals; and wherein Z² is hydrogen or a Z¹radical as defined above.
 5. An inorganic substrate as defined in claim4 wherein b is 0 and wherein R is an alkyleneoxyalkylene radical.
 6. Aninorganic substrate as defined in claim 5 wherein X is a methoxy radicaland wherein R is a propyleneoxymethylene radical.
 7. An inorganicsubstrate as defined in claim 2 wherein the polysulfide silicon couplingagent is a polysulfide siloxane homopolymer consisting essentially ofsiloxy units having the formula ##STR30##
 8. An inorganic substrate asdefined in claim 7 wherein R' is an alkyl radical, wherein R is analkylene or alkyleneoxyalkylene radical, and wherein n is 1 and t is 0.9. An inorganic substrate as defined in claim 8 wherein R is apropyleneoxymethylene radical and wherein Z is an organic amino radicalof the formula --NZ¹ Z² wherein Z¹ and Z² are taken individually and Z¹is an organic radical selected from the class consisting of alkyl, aryl,aralkyl, alkaryl and haloaryl radicals, hydroxy substituted alkyl, aryl,aralky and alkaryl radicals, alkoxy substituted alkyl, aryl, aralkyl andalkaryl radicals, mercapto substituted alkyl, aryl, aralkyl and alkarylradicals, amino substituted alkyl, aryl, aralkyl and alkaryl radicals,and hydrolyzable silyl substituted alkyl, aryl, aralkyl and alkarylradicals; and wherein Z² is hydrogen or a Z¹ radical as defined above.10. An inorganic substrate as defined in claim 2 wherein the polysulfidesilicon coupling agent is a polysulfide siloxane copolymer consistingessentially of at least one siloxy unit of the formula ##STR31## and atleast one siloxy unit represented by the formula ##STR32##
 11. Aninorganic substrate as defined in claim 10 wherein R' is a monovalenthydrocarbon radical, wherein R is an alkylene or alkyleneoxyalkyleneradical and wherein n is 1, and t is
 0. 12. An inorganic substrate asdefined in claim 11 wherein R is a propyleneoxymethylene radical andwherein Z is an organic amino radical of the formula --NZ¹ Z² wherein Z¹and Z² are taken individually and Z¹ is an organic radical selected fromthe class consisting of alkyl, aryl, aralkyl, alkaryl and haloarylradicals, hydroxy substituted alkyl, aryl, aralkyl and alkaryl radicals,alkoxy substituted alkyl, aryl, aralkyl and alkaryl radicals, mercaptosubstituted alkyl, aryl, aralkyl and alkaryl radicals, amino substitutedalkyl, aryl, aralkyl and alkaryl radicals, and hydrolyzable silylsubstituted alkyl, aryl, aralkyl and alkaryl radicals; and wherein Z² ishydrogen or a Z¹ radical as defined above.
 13. An inorganic substrate asdefined in claim 2 wherein the siliceous reinforcing material isselected from the class consisting of silica fillers, metal silicatefillers and glass fibers.
 14. An inorganic substrate as defined in claim2 wherein the episulfide substituted organosilicon coupling agent isemployed in the form of a solubilized solution.
 15. An inorganicsubstrate as defined in claim 2, wherein the episulfide substitutedorganosilicon coupling agent is employed is employed in the form of anaqueous composition.